1 /*
2 * Copyright (C) 2006 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 //
18 // Shared file mapping class.
19 //
20
21 #define LOG_TAG "filemap"
22
23 #include <utils/FileMap.h>
24 #include <utils/Log.h>
25
26 #include <stdio.h>
27 #include <stdlib.h>
28
29 #ifdef HAVE_POSIX_FILEMAP
30 #include <sys/mman.h>
31 #endif
32
33 #include <string.h>
34 #include <memory.h>
35 #include <errno.h>
36 #include <assert.h>
37
38 using namespace android;
39
40 /*static*/ long FileMap::mPageSize = -1;
41
42
43 /*
44 * Constructor. Create an empty object.
45 */
FileMap(void)46 FileMap::FileMap(void)
47 : mRefCount(1), mFileName(NULL), mBasePtr(NULL), mBaseLength(0),
48 mDataPtr(NULL), mDataLength(0)
49 {
50 }
51
52 /*
53 * Destructor.
54 */
~FileMap(void)55 FileMap::~FileMap(void)
56 {
57 assert(mRefCount == 0);
58
59 //printf("+++ removing FileMap %p %u\n", mDataPtr, mDataLength);
60
61 mRefCount = -100; // help catch double-free
62 if (mFileName != NULL) {
63 free(mFileName);
64 }
65 #ifdef HAVE_POSIX_FILEMAP
66 if (mBasePtr && munmap(mBasePtr, mBaseLength) != 0) {
67 ALOGD("munmap(%p, %d) failed\n", mBasePtr, (int) mBaseLength);
68 }
69 #endif
70 #ifdef HAVE_WIN32_FILEMAP
71 if (mBasePtr && UnmapViewOfFile(mBasePtr) == 0) {
72 ALOGD("UnmapViewOfFile(%p) failed, error = %ld\n", mBasePtr,
73 GetLastError() );
74 }
75 if (mFileMapping != INVALID_HANDLE_VALUE) {
76 CloseHandle(mFileMapping);
77 }
78 CloseHandle(mFileHandle);
79 #endif
80 }
81
82
83 /*
84 * Create a new mapping on an open file.
85 *
86 * Closing the file descriptor does not unmap the pages, so we don't
87 * claim ownership of the fd.
88 *
89 * Returns "false" on failure.
90 */
create(const char * origFileName,int fd,off64_t offset,size_t length,bool readOnly)91 bool FileMap::create(const char* origFileName, int fd, off64_t offset, size_t length,
92 bool readOnly)
93 {
94 #ifdef HAVE_WIN32_FILEMAP
95 int adjust;
96 off64_t adjOffset;
97 size_t adjLength;
98
99 if (mPageSize == -1) {
100 SYSTEM_INFO si;
101
102 GetSystemInfo( &si );
103 mPageSize = si.dwAllocationGranularity;
104 }
105
106 DWORD protect = readOnly ? PAGE_READONLY : PAGE_READWRITE;
107
108 mFileHandle = (HANDLE) _get_osfhandle(fd);
109 mFileMapping = CreateFileMapping( mFileHandle, NULL, protect, 0, 0, NULL);
110 if (mFileMapping == NULL) {
111 ALOGE("CreateFileMapping(%p, %lx) failed with error %ld\n",
112 mFileHandle, protect, GetLastError() );
113 return false;
114 }
115
116 adjust = offset % mPageSize;
117 adjOffset = offset - adjust;
118 adjLength = length + adjust;
119
120 mBasePtr = MapViewOfFile( mFileMapping,
121 readOnly ? FILE_MAP_READ : FILE_MAP_ALL_ACCESS,
122 0,
123 (DWORD)(adjOffset),
124 adjLength );
125 if (mBasePtr == NULL) {
126 ALOGE("MapViewOfFile(%ld, %ld) failed with error %ld\n",
127 adjOffset, adjLength, GetLastError() );
128 CloseHandle(mFileMapping);
129 mFileMapping = INVALID_HANDLE_VALUE;
130 return false;
131 }
132 #endif
133 #ifdef HAVE_POSIX_FILEMAP
134 int prot, flags, adjust;
135 off64_t adjOffset;
136 size_t adjLength;
137
138 void* ptr;
139
140 assert(mRefCount == 1);
141 assert(fd >= 0);
142 assert(offset >= 0);
143 assert(length > 0);
144
145 /* init on first use */
146 if (mPageSize == -1) {
147 #if NOT_USING_KLIBC
148 mPageSize = sysconf(_SC_PAGESIZE);
149 if (mPageSize == -1) {
150 ALOGE("could not get _SC_PAGESIZE\n");
151 return false;
152 }
153 #else
154 /* this holds for Linux, Darwin, Cygwin, and doesn't pain the ARM */
155 mPageSize = 4096;
156 #endif
157 }
158
159 adjust = offset % mPageSize;
160 try_again:
161 adjOffset = offset - adjust;
162 adjLength = length + adjust;
163
164 flags = MAP_SHARED;
165 prot = PROT_READ;
166 if (!readOnly)
167 prot |= PROT_WRITE;
168
169 ptr = mmap(NULL, adjLength, prot, flags, fd, adjOffset);
170 if (ptr == MAP_FAILED) {
171 // Cygwin does not seem to like file mapping files from an offset.
172 // So if we fail, try again with offset zero
173 if (adjOffset > 0) {
174 adjust = offset;
175 goto try_again;
176 }
177
178 ALOGE("mmap(%ld,%ld) failed: %s\n",
179 (long) adjOffset, (long) adjLength, strerror(errno));
180 return false;
181 }
182 mBasePtr = ptr;
183 #endif /* HAVE_POSIX_FILEMAP */
184
185 mFileName = origFileName != NULL ? strdup(origFileName) : NULL;
186 mBaseLength = adjLength;
187 mDataOffset = offset;
188 mDataPtr = (char*) mBasePtr + adjust;
189 mDataLength = length;
190
191 assert(mBasePtr != NULL);
192
193 ALOGV("MAP: base %p/%d data %p/%d\n",
194 mBasePtr, (int) mBaseLength, mDataPtr, (int) mDataLength);
195
196 return true;
197 }
198
199 /*
200 * Provide guidance to the system.
201 */
advise(MapAdvice advice)202 int FileMap::advise(MapAdvice advice)
203 {
204 #if HAVE_MADVISE
205 int cc, sysAdvice;
206
207 switch (advice) {
208 case NORMAL: sysAdvice = MADV_NORMAL; break;
209 case RANDOM: sysAdvice = MADV_RANDOM; break;
210 case SEQUENTIAL: sysAdvice = MADV_SEQUENTIAL; break;
211 case WILLNEED: sysAdvice = MADV_WILLNEED; break;
212 case DONTNEED: sysAdvice = MADV_DONTNEED; break;
213 default:
214 assert(false);
215 return -1;
216 }
217
218 cc = madvise(mBasePtr, mBaseLength, sysAdvice);
219 if (cc != 0)
220 ALOGW("madvise(%d) failed: %s\n", sysAdvice, strerror(errno));
221 return cc;
222 #else
223 return -1;
224 #endif // HAVE_MADVISE
225 }
226